This invention relates to check valves associated with fluid chambers or inflatable bladders and, more particularly, such valves as are formed of thermoplastic film material and which are adapted to be used in combination with a fluid pump or other bladder inflation device.
U.S. Pat. No. 3,133,696 to Mirando, discloses a plastic foam pump in an air-tight bladder for inflating the bladder and includes a flapper type inlet check valve 23 and duck-bill type outlet check valve 22.
U.S. Pat. No. 3,583,008 to Edwards, discloses a bulb-shaped, self-contained pump 36 connected to each of the inflatable compartments of an air mattress. The bulb relies upon a U-shaped spring and a coil spring 54 to expand the bulb after it has been compressed in each stroke of the pump.
U.S. Pat. No. 4,674,532 to Koyanagi, discloses a check valve for a balloon formed of a plurality of plastic film, including a pipe and at least one valve body formed as a pouch, laterally closed at one end.
U.S. Pat. No. 4,917,646 to Kieves, discloses a self-sealing air valve for a balloon formed by two sheets of plastic. One of the sheets is of substantially greater length than the other to provide a tab 62 for securing the valve in the stem of the balloon. The sheets are fitted together in such a way as to form an offset section 74 or throat.
It is the principal object of this invention to provide a wholly thermoplastic check valve and inflatable bladder combination of simpler, less inexpensive and more compact construction than the valves disclosed in the prior art and can be used for liquids as well as gases while, at the same time, being reliable in operation.
It is another object of this invention to provide a check valve of the above type which, because of its soft and pliable construction, lends itself to ease of co-assembly in various types of inflatable bladder applications.
It is a further object of this invention to provide a combination check valve and fluid pump of very low profile, especially adapted to be used in inflatable body support applications such as, inflatable athletic shoe liners, medical splints, intravenous needle holders for pediatric applications, athletic gloves, brassieres, back support belts and the like where compactness, flexability, comfort, convenience, durability and reliability are important.
It is still a further object of this invention to provide a check valve to prevent very high "spike" pressures from bleeding fluid from one bladder chamber to another chamber.